Abstract
Introduction: In case of a gas leakage, visualizations of gas clouds are frequently used by the
fire brigade to quickly understand where a gas cloud will spread. However, the effectiveness of
gas cloud visualization methods that are currently in use, can be improved. One of the main
obstacles in visualizing gas clouds is
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making an intuitive representation of the uncertainty
information, in combination with displaying intensity information, which both are important
for making a correct risk estimation of the situation. The objective of this study is to find the
most effective way to visualize a gas cloud, whereby uncertainty information and intensity of
the gas will be correctly integrated in the visualization. Moreover, because research has shown
that there is a relationship between cognitive skills and visualization task performance, the
current study will also investigate the relationship between task accuracy and completion time
of risk estimation within a gas cloud visualization and cognitive skills. Methods: Fifty-four
non-experts participated in an online experiment with two different gas cloud visualizations.
Four cognitive skills were measured: numeracy, visual working memory, visuospatial attention
and perceptual speed. All participants viewed the two types of gas cloud visualizations: the
Cone and the Tracks, and estimated the risk of 27 different locations within the visualization.
Repeated measures ANOVAs were carried out to measure the task accuracy. The task is
executed accurately when risk estimation decreases with a decrease in intensity level and a
increase in distance-to-center.Respectively, this mean that participants understand the intensity
level display and the spatial distribution of gas cloud probability. Moreover, a bivariate
Spearman’s Rho correlation was executed to study the relationship between cognitive skills and
visualization task accuracy and completion time. Results: Within both visualizations
participants significantly decreased their risk estimation with a decrease in intensity level, and
an increase in the distance-to-center. A significant relationship was found between perceptual
speed and task completion time. No significant relationship was found between the other
cognitive skills and task performance. Discussion: These results show that both visualizations
could be used as effective visualizations of gas clouds. Within our study the user characteristics
do not seem to have an influence on visualization task performance, although perceptual speed
is found to be related to completion time. Future research should investigate whether the same
results will be obtained when experts are used as participants (i.e. the fire brigade).
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